Gas charging and accumulation in deep coal measures of Daning-Jixian Block,Ordos Basin:insights from fluid inclusions and basin modeling  

作　　者：Zhanwei LI Song LI Dazhen TANG Shuling TANG Jiaosheng YANG Wei HOU 

机构地区：[1]School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083,China [2]Coal Reservoir Laboratory of National Engineering Research Center of CBM Development&Utilization,Beijing 100083,China [3]China Petroleum Exploration and Development Research Institute,Langfang 065007,China [4]National Engineering Research Center of China United Coalbed Methane Co.Ltd.,Beijing 100095,China [5]PetroChina Coalbed Methane Company Limited,Beijing 100028,China

出　　处：《Frontiers of Earth Science》2024年第4期696-713,共18页地球科学前沿(英文版)

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.42130802 and 42072198);the Fundamental Research Funds for the Central Universities(No.265QZ2021011);PetroChina Company Limited“14th Five Year Plan”Science and Technology Major Project(No.2021DJ2301);PetroChina Company Limited Science and Technology Project(No.2023-KJ-18).

摘　　要：Unconventional natural gas in deep coal measures has become an exploration and research hotspot in recent years.The exploration breakthrough of deep coalbed methane and tight sandstone gas in Daning-Jixian Block in the eastern Ordos Basin has revealed huge resource potential and commercial prospects in the deep Upper Paleozoic Carboniferous-Permian coal measures.However,the ambiguity of gas accumulation in deep coal measures has restricted exploration and development.Based on a series of tests for fluid inclusions,including petrographic observation,Raman spectroscopy analysis,and microthermometry,combined with the burial-thermal evolution history recovered from basin modeling,this study aims to clarify the timing of gas accumulation in deep coal measures.The results show four types of secondary fluid inclusions in the deep coal measure sandstone layers of Daning-Jixian Block,including CH4-rich inclusions,C2+hydrocarbons-bearing inclusions,CO2-bearing inclusions,and aqueous inclusions.The main formation stage of fluid inclusions corresponded to the mesodiagenesis stage of the deep coal measure sandstone,and the coeval assemblages of fluid inclusions vary due to the recording of gas charging in different maturity stages of coal measure source rocks.This study suggests that tight sandstone gas accumulation in deep coal measures was a continuous charging process with one period-multiple episodes in Daning-Jixian Block,and occurred mainly during the Early Cretaceous(137−127 Ma BP).The results of this study contribute to further understanding of gas accumulation mechanisms in deep coal measures.

关 键 词：gas accumulation/deep coal measures/fluid inclusions/basin modeling/Daning-Jixian Block 

分 类 号：P61[天文地球—矿床学]